Interposer substrate and method of fabricating the same

ABSTRACT

The invention provides an interposer substrate and a method of fabricating the same. The method includes: etching a carrier to form a recessed groove thereon; filling a dielectric material in the recessed groove to form a first dielectric material layer, or forming a patterned first dielectric material layer on the carrier; forming a first wiring layer, a first conductive block and a second dielectric material layer on the carrier and the first dielectric material layer sequentially, with the first wiring layer and the first conductive block embedded in the second dielectric material layer; and forming a second wiring layer and a second conductive block on the second dielectric material layer. A coreless interposer substrate having fine pitches is thus fabricated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of application Ser. No. 14/706,101 filed on May 7, 2015, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to interposer substrates, and, more particularly, to an interposer substrate and a method of fabricating the interposer substrate.

2. Description of Related Art

With the development in miniaturization for semiconductor packages, a typical printed circuit board (PCB) has smaller surface available to accommodate semiconductor packages. Therefore, a Package on Package (PoP) is developed having multiple packaging structures, each being stacked on top of the other in order to meet the high density requirement.

Traditional stacked packages are formed by stacking a semiconductor package via a plurality of solder balls such that it is electrically connected to another semiconductor package. However due to the limitation of the fabricating process, a certain size and distance must remain for the solder balls, as a result, the electrical external connection points would be reduced as only a limited area of the package is available, which leads to an increase in thickness of the overall package structure.

Referring to FIG. 1, in order to increase I/O number and meet the low-profile and compact-size requirements for the stacked package structures, an interposer substrate 10 is provided between a first semiconductor package 1A and a second semiconductor package 1B, and a first wiring layer 11 and a second wiring layer 12 are formed on the first surface and second surface of the interposer 10, respectively. The interposer substrate 10 has conductive vias 13 for electrically connecting the first wiring layer 11 with the second wiring layer 12.

FIGS. 2A-2F illustrate a method of fabricating an interposer substrate.

As shown in FIG. 2A, a core board 20 is provided. The core board 20 has a first surface 20 a and an opposing second surface 20 b. A plurality of vias 20 c are formed on the core board 20 and penetrate the first and second surfaces 20 a and 20 b. A metal layer 21 is plated on the first surface 20 a, the second surface 20 b and the vias 20 c of the core board 20.

As shown in FIG. 2B, the metal layer 21 on the first surface 20 a and second surface 20 b are patterned to form the first wiring layer 21 a and second wiring layer 21 b that are electrically connected through the metal layer in the vias (i.e., the conductive vias 21 c). An insulating layer (a solder mask layer) 22 is formed on the first wiring layer 21 a and the second wiring layer 21 b, and a plurality of openings are formed on the insulating layer to expose a portion of the first wiring layer 21 a and the second wiring layer 21 b.

As shown in FIG. 2C, a conductive layer 23 and a resist layer 24 are formed on the insulating layer 22 of the first surface 20 a and the second surface 20 b of the core board 20.

As shown in FIG. 2D, the resist layer 24 is patterned to form a plurality of openings to expose a portion of the second wiring layer 21 b. An electroplating process is performed to form in the openings of the resist layer 24 a conductive material that is electrically connected with the second wiring layer 21 b.

As shown in FIG. 2E, the resist layer 24 and the conductive layer 23 covered by the resist layer 24 are removed to form an interposer substrate.

However, the method is complex and the cost thereof is high. The additionally disposed conductive layer is likely to deteriorate the electrical performance of the interposer substrate. In addition, the thickness of the interposer substrate is also limited, such that when the thickness is smaller (such as under 130 μm), it is difficult to be fabricated and damages could easily occur. Further the design of the wiring would be limited by the line width/line space (L/S). The yield may be influenced when L/S is lower than 25/25 μm.

Hence, there is an urgent need to solve the foregoing problems encountered in the prior art.

SUMMARY OF THE INVENTION

In view of the foregoing drawbacks, the present invention provides a method of fabricating an interposer substrate, comprising: forming a plurality of recessed grooves on a carrier, and forming a first dielectric material layer in the recessed grooves; forming a first wiring layer on the carrier and the first dielectric material layer; forming a plurality of first conductive blocks on the first wiring layer; covering the first wiring layer and the first conductive blocks with a second dielectric material layer, with terminal portions of the first conductive blocks exposed from the second dielectric material layer; forming on the second dielectric material layer a second wiring layer that is electrically connected with the first conductive blocks; forming second conductive blocks on the second wiring layer; and removing the carrier.

The present invention provides an interposer substrate, comprising: a second dielectric material layer having opposing first and second surfaces; a first wiring layer embedded in the second dielectric material layer and having a first surface flush with the first surface of the second dielectric material layer and a second surface opposing to the first surface of the first wiring layer; a first dielectric material layer formed on the first surface of the second dielectric material layer and having a plurality of openings, from which a portion of the first wiring layer is exposed; a plurality of first conductive blocks embedded in the second dielectric material layer and having first terminal surfaces connected to the second surface of the first wiring layer and second terminal surfaces opposing to the first terminal surfaces and flush with the second surface of the dielectric material layer; a second wiring layer formed on the second surface of the second dielectric material layer and having a first surface connected to the second terminal surfaces of the first conductive blocks and a second surface opposing to the first surface of the second wiring layer; and a plurality of second conductive blocks formed on the second surface of the second wiring layer.

The present invention provides a method of fabricating an interposer substrate, comprising: forming on a carrier a first dielectric material layer that has a plurality of openings, from which the carrier is exposed; forming a first wiring layer on the carrier and the first dielectric material, with a first portion of the first wiring layer formed in the openings of the first dielectric material layer and a second portion the first wiring layer formed on the first dielectric material layer; forming a plurality of first conductive blocks on the first wiring layer; covering the first dielectric material layer, the first wiring layer and the first conductive blocks with a second dielectric material layer, with terminal portions of the first conductive blocks exposed from the second dielectric material layer; forming on the second dielectric material layer a second wiring layer that is electrically connected with the first conductive blocks; forming a plurality of second conductive blocks on the second wiring layer; and removing the carrier.

The present invention provides an interposer substrate, comprising: a first dielectric material layer having opposing first and second surfaces and a plurality of openings penetrating the first and second surfaces; a first wiring layer having a first portion formed on the second surface of the first dielectric material layer and a second portion formed in the openings of the first dielectric material layer and exposed from the first surface of the first dielectric material layer; a plurality of first conductive blocks formed on the first wiring layer; a second dielectric material layer covering the second surface of the first dielectric material layer and the first wiring layer and encapsulating the first conductive blocks, with terminal portions of the first conductive blocks exposed from the second dielectric material layer; a second wiring layer formed on the second dielectric material layer and electrically connected with the first conductive blocks; and a plurality of second conductive blocks formed on the second wiring layer.

In summary, the present invention provides an interposer substrate and a method of fabricating the same, which are characterized by forming recessed grooves on a carrier by an etching method, with a first dielectric material layer formed in the recessed grooves, forming a patterned first dielectric material layer on the carrier, forming a first wiring layer, first conductive blocks, and a second dielectric material layer on the carrier and the first dielectric material layer, with the first wiring layer and first conductive blocks embedded in the second dielectric material layer, and forming second wiring layer and second conductive blocks on the second dielectric material layer, to form a coreless interposer substrate having and fine pitches, so as to meet the low-profile and compact-size requirements. In addition, the present invention also solves the problem that the design limitation due to line width/line space (L/S) in prior art. Besides only a portion of the first wiring layer is exposed, for mounting and electrically connecting the external electronic elements, without a need of disposing an insulating layer (solder mask layer), as well as any additional conductive layer, as a result the fabricating process is simplified and the cost is reduced.

BRIEF DESCRIPTION OF DRAWINGS

The present invention can be more fully understood by reading the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein:

FIG. 1 is a schematic cross-sectional view showing a conventional stacked package structure;

FIGS. 2A-2E are schematic cross-sectional views showing a conventional interposer substrate;

FIGS. 3A-3K are schematic cross-sectional views showing an interposer substrate in accordance with a first embodiment of the present invention;

FIGS. 4A and 4B are schematic cross-sectional views showing an interposer substrate in accordance with a second embodiment of the present invention;

FIGS. 5A-5I are schematic cross-sectional views showing an interposer substrate in accordance with a third embodiment of the present invention; and

FIGS. 6A and 6B are schematic cross-sectional views showing an interposer substrate in accordance with a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is described in the following with specific embodiments, so that one skilled in the pertinent art can easily understand other advantages and effects of the present invention from the disclosure of the present invention.

It should be noted that all the drawings are not intended to limit the present invention. Various modification and variations can be made without departing from the spirit of the present invention. Further, terms, such as “on”, “first”, “second” and “top”, “bottom” and etc., are merely for illustrative purpose and should not be construed to limit the scope of the present invention.

FIGS. 3A-3K are schematic cross-sectional views of an interposer substrate according to a first embodiment of the present invention.

As shown in FIG. 3A, a carrier 30 and a first resist layer 31 covering the carrier 30 are provided. A pattering process is performed on the first resist layer 31 a to forming a plurality of openings for exposing the carrier 30. The carrier 30 is, but not limited to, a substrate such as a copper foil substrate.

As shown in FIG. 3B, an etching method is performed to remove a portion of the carrier 30 covered by the first resist layer 31 a, to form a plurality of recessed grooves 300 on the carrier 30.

As shown in FIG. 3C, the first resist layer 31 a is removed and the recessed grooves 300 are filled with a dielectric material, so as to form a first dielectric material layer 32 a. The first dielectric material layer can be formed in the recessed grooves 300 via a molding, a coating, or a lamination method. The dielectric material can be epoxy resin for instance.

As shown in FIG. 3D, a patterned second resist layer 31 b is formed on the carrier 30 and the first dielectric material layer 32 a, and the second resist layer 31 b has a plurality of openings to expose the first dielectric material layer 32 a and a portion of the carrier 30. Subsequently, a first wiring layer 33 a is formed in the openings of the second resist layer 31 b.

As shown in FIG. 3E, a third resist layer 31 c is formed and covers the first wiring layer 33 a and the second resist layer 31 b, and is patterned to form a plurality of openings on the third resist layer 31 c to expose a portion of the first wiring layer 33 a. Subsequently, a plurality of first conductive blocks 34 a are formed in the openings of the third resist layer 31 c.

As shown in FIG. 3F, the second resist layer 31 b and the third resist layer 31 c are removed to expose the first wiring layer 33 a and the first conductive blocks 34 a.

As shown in FIG. 3G, the first dielectric material layer 32 a, the first wiring layer 33 a and the first conductive blocks 34 a are covered with a second dielectric material layer 32 b, such that the terminal portions of the first conductive blocks 34 a are exposed from the second dielectric material layer 32 b.

As shown in FIG. 3H, the second dielectric material layer 32 b is covered with a fourth resist layer 31 d, and the fourth resist layer 31 d is patterned to form a plurality of openings for exposing the first conductive blocks 34 a and a portion of the second dielectric material layer 32 b. A second wiring layer 33 b is formed in the openings of the fourth resist layer 31 d. The second wiring layer 33 b is electrically connected with the first wiring layer 33 a via the first conductive blocks 34 a.

As shown in FIG. 3I, the fourth resist layer 31 d and the second wiring layer 33 b are covered with a fifth resist layer 31 e, and the fifth resist layer 31 e is patterned to form a plurality of openings for exposing a portion of the second wiring layer 33 b. Second conductive blocks 34 b are formed in the openings of the fifth resist layer 31 e and electrically connected with the second wiring layer 33 b.

As shown in FIG. 3J, the fifth resist layer 31 e and the fourth resist layer 31 d are removed, for exposing the second wiring layer 33 b and the second conductive blocks 34 b.

As shown in FIG. 3K, the carrier 30 is removed, to expose a portion of the first wiring layer 33 a, so as to complete the fabrication of the interposer substrate according to the present invention. In addition, it is also applicable to etch away the central portion of the carrier, to form a frame-type carrier on the retained first dielectric material layer, to function as a supporting means for the interposer substrate.

Referring to FIG. 3K, the interposer substrate according to the present invention comprises: a first dielectric material layer 32 a, a second dielectric material layer 32 b, a first wiring layer 33 a, a second wiring layer 33 b, first conductive blocks 34 a, and second conductive blocks 34 b.

The second dielectric material layer 32 b has a first surface 321 b and an opposing second surface 322 b.

The first wiring layer 33 a has a first surface 331 a and an opposing second surface 332 a.

The first wiring layer 33 a is embedded in the second dielectric material layer 32 b, and the first surface 331 a of the first wiring layer 33 a is flush with the first surface 321 b of the second dielectric material layer 32 b.

The first dielectric material layer 32 a is formed on the first surface 321 b of the second dielectric material layer 32 b, and the first dielectric material layer 32 a has a plurality of openings to expose a portion of the first wiring layer 33 a. The partly exposed first wiring layer 33 a, such as bonding pads served as an electrical connecting means for electrically connecting external electronic elements (such as semiconductor packages) with the bonding pads via conductive elements such as solder balls. Each of the first conductive blocks 34 a has an opposing first terminal portion 341 a coupled to the second surface 332 a of the first wiring layer 33 a, and an opposing second terminal portion 342 a flush with the second surface 322 b of the second dielectric material layer 32 b.

The second wiring layer 33 b has a first surface 331 b and an opposing second surface 332 b. The second wiring layer 33 b is formed on the second surface 322 b of the second dielectric material layer 32 b, and a portion of the first surface 331 b of the second wiring layer 33 b is coupled to the second terminal portion 342 a of the first conductive blocks 34 a.

The second conductive blocks 34 b are formed on the second surface 332 b of the second wiring layer 33 b.

FIGS. 4A-4B are schematic cross-sectional views showing a method of fabricating the interposer substrate in accordance with a second embodiment of the present invention.

As shown in FIG. 4A, after the fifth resist layer and the fourth resist layer are removed to expose the second wiring layer 33 b and second conductive blocks 34 b corresponding in FIG. 3J, an insulative protection layer 35 is formed to cover the second dielectric material layer 32 b, the second wiring layer 33 b and the second conductive blocks 34 b.

As shown in FIG. 4B, a portion of the insulative protection layer 35 is removed to expose the second conductive blocks 34 b, and the carrier 30 is removed to expose the first dielectric material layer 32 a and a portion of the first wiring layer 33 a.

FIGS. 5A-5I are schematic cross-sectional views showing an interposer substrate in accordance with a third embodiment of the present invention.

As shown in FIG. 5A, a carrier 50 is provided with a patterned first dielectric material layer 52 a formed on the surface of the carrier 50, and a plurality of openings are formed on the first dielectric material layer 52 a to expose a portion of the carrier 50.

As shown in FIG. 5B, a patterned first resist layer 51 a is formed on the carrier 50 and the first dielectric material layer 52 a, and a plurality of openings are formed on the patterned first resist layer 51 a to expose a portion of the carrier 50 and a portion of the first dielectric material layer 52 a. A first wiring layer 53 a is formed in the openings of the first resist layer 51 a. The openings for exposing the first resist layer correspond in position to the openings of the first dielectric material layer 52 a.

As shown in FIG. 5C, a patterned second resist layer 51 b is formed on the first resist layer 51 a and the first wiring layer 53 a, and has a plurality of openings for exposing a portion of the first wiring layer 53 a. First conductive blocks 54 a are formed in the openings of the second resist layer 51, and electrically connected with the first wiring layer 53 a. The openings of the second resist layer correspond in position to the openings of the first resist layer 51 a.

As shown in FIG. 5D, the second resist layer 51 b and the first resist layer 51 a are removed to expose the first dielectric material layer 52 a, the first wiring layer 53 a, and the first conductive blocks 54 a.

As shown in FIG. 5E, the first dielectric material layer 52 a, the first wiring layer 53 a, and the first conductive blocks 54 a are covered with a second dielectric material layer 52 b, with the terminal portions of the first conductive blocks 54 a exposed from the second dielectric material layer 52 b.

As shown in FIG. 5F, a patterned third resist layer 51 c is formed on the second dielectric material layer 52 b, and has openings for exposing the first conductive blocks 54 a and a portion of the second dielectric material layer 52 b. A second wiring layer 53 b is formed in the openings of the third resist layer 51 c, and electrically connected with the first conductive blocks 54 a.

As shown in FIG. 5G, a patterned fourth resist layer 51 d is formed on the third resist layer 51 c and the second wiring layer 53 b, and has a plurality of openings to expose the second wiring layer 53 b. Second conductive blocks 54 b are formed in the openings of the fourth resist layer 51 d, and electrically connected with the second wiring layer 53 b.

As shown in FIG. 5H, the fourth resist layer 51 d and the third resist layer 51 c are removed to expose the second wiring layer 53 b and second conductive blocks 54 b.

As shown in FIG. 5I, the carrier 50 is removed to expose the first dielectric material layer 52 a and a portion of the first wiring layer 53 a, so as to complete the fabrication of the interposer substrate according to the present invention. In addition, it is also applicable to etch away the central portion of the carrier, to form a frame-type carrier on the remaining first dielectric material layer, to function as a supporting means for the interposer substrate.

Referring to FIGS. 5I, the interposer substrate according to the present invention comprises: a first dielectric material layer 52 a, a second dielectric material layer 52 b, a first wiring layer 53 a, a second wiring layer 53 b, first conductive blocks 54 a, and second conductive blocks 54 b.

The first dielectric material layer 52 a has a first surface 521 a and an opposing second surface 522 a, and a plurality of openings penetrating the first surface 521 a and the second surface 522 a.

The first wiring layer 33 a has a first surface 531 a and an opposing second surface 532 a. A portion of the first wring layer 53 a is formed on the second surface 522 a of the first dielectric material layer 52 a, and a portion of the first surface 531 a is formed in the openings of the first dielectric material layer 52 a and is flush with the first surface 521 a of the first dielectric material layer 52 a. The partly exposed first wiring layer 53 a, such as bonding pads served as an electrical connecting means for electrically connecting external electronic elements (such as semiconductor packages) with the bonding pads via conductive elements such as solder balls.

The first conductive block 54 a are formed on the second surface 532 a of the first wiring layer 53 a and electrically connected with the first wiring layer 53 a.

The second dielectric material layer 52 b covers the second surface 522 a of the first dielectric material layer 52 a and the second surface 532 a of the first wiring layer 53 a and encapsulates the first conductive bumps 54 a in such a way that the terminal portions of the first conductive bumps 54 a are exposed from the second dielectric material layer 52 b.

The second wiring layer 353 b is formed on the second dielectric material layer 52 b, and electrically connected with first conductive blocks 54 a.

The second conductive blocks 54 b are formed on the second wiring layer 53 b.

FIGS. 6A-6B are schematic cross-sectional views showing an interposer substrate in accordance with a fourth embodiment of the present invention.

As shown in FIG. 6A, the fourth resist layer and the third resist layer are removed, as did in FIG. 5H, to expose the second wiring layer 54 b, and the carrier 50 is removed to expose the first dielectric material layer 52 a and a portion of the first wiring layer 53 a.

In summary, the present invention provides an interposer substrate and a method of fabricating the same, which are characterized by forming recessed grooves on a carrier by an etching method, with a first dielectric material layer formed in the recessed grooves, forming a patterned first dielectric material layer on the carrier, forming a first wiring layer, first conductive blocks, and a second dielectric material layer on the carrier and the first dielectric material layer, with the first wiring layer and first conductive blocks embedded in the second dielectric material layer, and forming a second wiring layer and second conductive blocks on the second dielectric material layer, to form a coreless interposer substrate having and fine pitches, so as to meet the low-profile and compact-size requirements. In addition, the present invention also solves the problem that the design limitation due to line width/line space (L/S) in prior art. Besides only a portion of the first wiring layer is exposed, for mounting and electrically connecting the external electronic elements, without a need of disposing an insulating layer (solder mask layer), as well as any additional conductive layer, as a result the fabricating process is simplified and the cost is reduced.

The present invention has been described using exemplary preferred embodiments. However, it is to be understood that the scope of the present invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements. The scope of the claims, therefore, should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

What is claimed is:
 1. A method of fabricating an interposer substrate, comprising: forming on a carrier a first dielectric material layer having a plurality of openings, from which the carrier is exposed; forming a first wiring layer on the carrier, wherein a position of the first wiring layer corresponds to the plurality of openings of the first dielectric material layer; forming a plurality of first conductive blocks on the first wiring layer; covering the first wiring layer and the first conductive blocks with a second dielectric material layer, with terminal portions of the first conductive blocks exposed from the second dielectric material layer; forming on the second dielectric material layer a second wiring layer electrically connected with the first conductive blocks; forming a plurality of second conductive blocks on the second wiring layer; and forming an insulative protection layer on the second dielectric material layer, the second wiring layer and the second conductive blocks, from which the second conductive blocks are exposed, wherein the insulative protection layer has at least a concave portion formed between two of the second conductive blocks; and removing the carrier.
 2. The method of claim 1, further comprising, prior to forming the first wiring layer on the carrier, forming a plurality of recessed grooves on the carrier, and forming the first dielectric material layer in the recessed grooves, wherein the openings of the first dielectric material layer are adjacent to the recessed grooves, and wherein the recessed grooves are formed by forming on the carrier a first resist layer that has a plurality of openings, from which the carrier is exposed, and etching a portion of the carrier that is not covered by the first resist layer.
 3. The method of claim 1, wherein the first wiring layer is formed by forming on the carrier and the first dielectric material layer a second resist layer that has a plurality of openings, from which a portion of the first dielectric material layer and a portion of the carrier are exposed, and forming the first wiring layer in the openings of the second resist layer.
 4. The method of claim 3, wherein the first conductive blocks are formed by forming on the first wiring layer and the second resist layer a third resist layer that has a plurality of openings, from which a portion of the first wiring layer is exposed, and forming the first conductive blocks in the openings of the third resist layer.
 5. The method of claim 1, wherein the second wiring layer is formed by forming on the second dielectric material layer a fourth resist layer that has a plurality of openings, from which the first conductive blocks and a portion of the second dielectric material layer are exposed, and forming in the openings of the fourth resist layer the second wiring layer that is electrically connected with the first wiring layer via the exposed terminal portions of the first conductive blocks.
 6. The method of claim 5, wherein the second conductive blocks are formed by forming on the fourth resist layer and on second wiring layer a fifth resist layer that has a plurality of openings, from which a portion of the second wiring layer is exposed, and forming in the openings of the fifth resist layer the second conductive blocks that are electrically connected with the second wiring layer.
 7. The method of claim 1, wherein the first wiring layer has a surface flush with a surface of the second dielectric material layer.
 8. The method of claim 1, further comprising: forming the first wiring layer on the carrier and the first dielectric material, with a first portion of the first wiring layer formed in the openings of the first dielectric material layer and a second portion the first wiring layer formed on the first dielectric material layer.
 9. The method of claim 8, wherein the first wiring layer is formed by forming on the carrier and the first dielectric material layer a first resist layer that has a plurality of openings, from which the carrier and the first dielectric material layer are exposed, and forming the first wiring layer in the openings of the first resist layer.
 10. The method of claim 9, wherein the first conductive blocks are formed by forming on the first resist layer and the first wiring layer a second resist layer that has a plurality of openings, from which the first wiring layer is exposed, and forming in the openings of the second resist layer the first conductive blocks that are electrically connected with the first wiring layer.
 11. The method of claim 8, wherein the second wiring layer is formed by forming on the second dielectric material layer a third resist layer that has a plurality of openings, from which the first conductive blocks and the second dielectric material layer are exposed, and forming in the openings of the third resist layer the second wiring layer that is electrically connected with the first conductive blocks.
 12. The method of claim 11, wherein the second conductive blocks is formed by forming on the third resist layer and the second wiring layer a fourth resist layer that has a plurality of openings, from which the second wiring layer is exposed, and forming in the openings of the fourth resist layer the second conductive blocks that are electrically connected with the second wiring layer.
 13. An interposer substrate, comprising: a second dielectric material layer having opposing first and second surfaces; a first wiring layer embedded in the second dielectric material layer and exposed from the first surface of the second dielectric material layer; a first dielectric material layer formed on the first surface of the second dielectric material layer and the first wiring layer, wherein the first dielectric material layer has a plurality of openings, from which a portion of the first wiring layer is exposed; a plurality of first conductive blocks embedded in the second dielectric material layer and having first terminal surfaces connected to the first wiring layer and second terminal surfaces opposing to the first terminal surfaces and flush with the second surface of the second dielectric material layer; a second wiring layer formed on the second surface of the second dielectric material layer and having a first side connected to the second terminal surfaces of the first conductive blocks and a second side opposing to the first surface of the second wiring layer; a plurality of second conductive blocks formed on the second side of the second wiring layer; and an insulative protection layer formed on the second surface of the second dielectric material layer, the second wiring layer and the second conductive blocks, wherein an end of the second conductive blocks is exposed from the insulative protection layer, and the insulative protection layer has at least a concave portion formed between two of the second conductive blocks.
 14. The interposer substrate of claim 13, further comprising a frame-type carrier formed on the first dielectric material layer.
 15. The interposer substrate of claim 13, wherein the portion of the first wiring layer exposed from the openings of the first dielectric material layer serves as bonding pads, for an external electronic component to be disposed on and electrically connected with the bonding pads via a plurality of conductive elements.
 16. The interposer substrate of claim 13, wherein the first wiring layer has a first portion embedded in the second dielectric material layer and a second portion formed in the openings of the first dielectric material layer.
 17. The interposer substrate of claim 13, wherein the first wiring layer having a surface flush with the first surface of the second dielectric material layer. 